Provided is a conjugated block copolymer that is capable of morphology control and that can achieve superior conversion efficiency. A π-electron conjugated block copolymer contiguously or non-contiguously bonding polymer block (A) involving a monomer unit having in a portion of a chemical structure at least one heteroaryl skeleton selected from a thiophene, a fluorine, a carbazole, a dibenzosilole and a dibenzogermole; and a polymer block (B) involving a monomer unit similarly having at least one heteroaryl skeleton; wherein the polymer block (A) comprises a homopolymer block of a monomer unit having a substituent RnA that is an alkoxy group or an alkyl group having 1-18 carbon atoms, and the polymer block (B) comprises a copolymer block of at least two different each other types of monomer units having substituent RnB selected from an alkoxy group or an alkyl group having 1-18 carbon atoms, which may be substituted with an alkoxy group, a halogen atom, a hydroxyl group, an amino group, a thiole group, a silyl group, an ester group, an aryl group, hetero aryl group.Related Terms:Photoelectric ConversionConversion EfficiencyAlkyl GroupCarbazoleMorphologySkeletonAtomsBlock CopolymerContiguousPolymerCarbon AtomsElectric ConversionConjugated BMonomer

BACKGROUND ART

Organic thin film solar cells which are produced by coating with a method using a polymer material that is soluble in solvent has attracted much attention, because they can be manufactured at low cost when compared with inorganic solar cells which are mainstream solar cells that have been made of polycrystalline silicon, amorphous silicon, compound semiconductor, etc.

The organic thin film solar cell, which is one of the photoelectric conversion elements, generally has a photoelectric conversion active layer which has a bulk heterojunction structure formed with a mixture of a conjugated polymer and an electron accepting material. As a specific example, there is an organic thin film solar cell having a photoelectric conversion active layer including a mixture of poly(3-hexylthiophene) (an conjugated polymer) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM), a fullerene derivative which is an electron accepting material (Non-Patent Document 1).

In the bulk heterojunction structure, incident light entering from the transparent electrode is absorbed by an electron accepting material and a conjugated polymer to generate an exciton which is a bound state of an electron and a hole. The generated exciton moves to the heterojunction interface where the electron accepting material abuts on the conjugated polymer, to charge-separate into an electron and a hole. Holes and electrons are then each transported through the conjugated polymer phase and the electron accepting material phase, and are then taken out from the electrode. Therefore, in order to improve the conversion efficiency of organic thin film solar cells, the key point is how to control the morphology which is formed during phase separation from the conjugated polymer and the electron accepting material both of which form a bulk heterojunction structure.

As a superior method for controlling the morphology of the electron accepting material and the conjugated polymer, a method in which a conjugated block copolymer is used has been known. For example, organic thin film solar cells have been reported, in which a fullerene derivative is used as an electron accepting material, and as a conjugated block copolymer, a diblock copolymer made from 3-hexylthiophene and 3-(2-ethylhexyl)thiophene (Non-Patent Document 2), a diblock copolymer made from 3-hexylthiophene and 3-(phenoxymethyl)thiophene (Non-Patent Document 3), a diblock copolymer made from 3-butylthiophene and 3-octylthiophene (Non-Patent Document 4), or a diblock copolymer made from 3-hexylthiophene and 3-cyclohexylthiophene (Non-Patent Document 5) is used respectively. Further, an organic thin film solar cell element using a conjugated block copolymer having a skeleton different from the polythiophene has been disclosed in order to achieve high conversion efficiency (Patent Document 1).

SUMMARY

The organic thin film solar cells using conjugated block copolymer listed in the prior art documents mentioned above, are allowed to control morphology to some extent, but the conversion efficiency has remained low at around only 2 to 3 percent. The present invention was made to solve such problems and to provide a conjugated block copolymer capable of controlling morphology and expressing excellent conversion efficiency, and also to provide a photoelectric conversion element including an electron accepting material and a conjugated block copolymer.

Means to Solve the Problems

The present invention which was made to achieve the previously described objects is a π-electron conjugated block copolymer contiguously or non-contiguously bonding a polymer block (A) involving a monomer unit having in a portion of a chemical structure at least one heteroaryl skeleton selected from a thiophene, a fluorene, a carbazole, a dibenzosilole and a dibenzogermole; and a polymer block (B) involving a monomer unit similarly having at least one heteroaryl skeleton; wherein the polymer block (A) comprises a homopolymer block of a monomer unit having a substituent RnA that is an alkoxy group or an alkyl group having 1-18 carbon atoms, and the polymer block (B) comprises a copolymer block of at least two different each other types of monomer units having substituents RnB selected from an alkoxy group or an alkyl group having 1-18 carbon atoms, which may be substituted with an alkoxy group, a halogen atom, a hydroxyl group, an amino group, a thiol group, a silyl group, an aryl group, an ester group or a heteroaryl group.

The present invention is the π-electron conjugated block copolymer, which is characterized in that the heteroaryl skeleton of the monomer unit that constitutes the polymer block (A) and the polymer block (B) is a group having at least one thiophene ring in a portion of the chemical structure.

The present invention is the π-electron conjugated block copolymer, which is characterized in that the polymer block (A) or the polymer block (B) includes a monomer unit of -a-b-, and the -a- has any one of groups represented by chemical formulas (1)-(8) below,

the -b- has any one of groups represented by the chemical formulas (9)-(19) below.

In the formulas (1)-(19) described above, V1 is nitrogen (—NR1—), oxygen (—O—) or sulfur (—S—); V2 is carbon (—CR12—), nitrogen (—NR1—), silicone (—SiR12—) or germanium (—GeR12—); V3 is an aryl group or hetero aryl group represented by —(Ar)q-; V4 is nitrogen (—NR1—), oxygen (—O—) or —CR2═CR2—; and V5 is oxygen (O) or sulfur (S). R1 is each independently an alkyl group having 1-18 carbon atoms which may be substituted, R2 is each independently a hydrogen atom or an alkyl group having 1-18 carbon atoms which may be substituted, R3 is each independently an alkoxy group or an alkyl group having 1-18 carbon atoms which may be substituted, R4 is each independently a hydrogen atom, a halogen atom, or an aryl group or an alkyl group having 1-18 carbon atoms which may be substituted, R5 is an aryl group, an alkylcarbonyl group, an alkyloxy carbonyl group, or an alkyl group having 1-18 carbon atoms which may be substituted, and R6 is a hydrogen atom or a halogen atom.

p is an integer of 1-3, and q represents an integer of 0-3.

Here, at least one of R1-R5 of monomer unit -a-b-, which is included in the polymer block (A), is RnA, and at least one of R1-R5 of monomer unit -a-b-, which is included in the polymer block (B), is RnB that may be substituted with an alkoxy group, a halogen atom, a hydroxyl group, an amino group, a thiol group, a silyl group, an ester group, an aryl group or a heteroaryl group.

The present invention is the π-electron conjugated block copolymer, which is characterized in that the monomer unit -a-b- is any one of groups selected from the following chemical formulas (20)-(31).

In the formulas (20)-(31), V2 is a carbon (—CR12—), nitrogen (—NR1—), silicon (—SiR12—) or germanium (—GeR12), V3 is an aryl group or a heteroaryl group represented by —(Ar)q-. R1, R2, R3, R4, R5 and R6 are the same as defined above. q represents an integer of 0-3. However, at least one of R1-R5 of the monomer unit -a-b-, which is included in the polymer block (A) is RnA. At least one of R1-R5 of the monomer unit -a-b-, which is included in the polymer block (B), is RnB that may be substituted with an alkoxy group, a halogen atom, a hydroxyl group, an amino group, a thiol group, a silyl group, an ester group, an aryl group or a heteroaryl group.

The present invention is the π-electron conjugated block copolymer, which is characterized in that a polymer block that including the monomer unit of -a-b- is both the polymer block (A) and the polymer block (B).

The present invention is the π-electron conjugated block copolymer, which is characterized in that the polymer block (B) is a random copolymer.

The present invention is the π-electron conjugated block copolymer, which is characterized in that the random copolymer comprises a plurality of different types of monomer units -a-b- from each other.

The present invention which was made to achieve the object of the present invention is a composition comprising an electron accepting material and the π-electron conjugated block copolymer described above.

Similarly, the present invention which was made to achieve the object of the present invention is a photoelectric conversion element comprising a layer essentially consisting of the composition described above.

The present invention is the photoelectric conversion element, in which the electron accepting material comprises a fullerene or/and a derivative thereof.

Advantageous Effect of the Invention

When the present π-electron conjugated block copolymer is used in a photoelectric conversion element together with an electron accepting material, an increase in the current value and a decrease in the resistance can be realized, and performance is significantly improved.

MODE FOR CARRYING OUT THE INVENTION

Preferred embodiment for carrying out the present invention will be precisely explained below, but the scope of the present invention is not limited to these embodiments.

In the present π-electron conjugated block copolymer, the polymer block (A) and polymer block (B) are combined or bonded, and a main chain skeleton of its monomer unit is a divalent group exhibiting a π-electron conjugation. The monomer unit has at least, in a portion of its chemical structure, one heteroaryl skeleton selected from a thiophene, a fluorene, a carbazole, a dibenzosilole, and a dibenzogermole. As the π-electron conjugated compounds having a thiophene ring in a portion of the chemical structure, for example, thiophene, cyclopentadithiophene, dithieno pyrrole, dithienosilole, dithienogermole, benzodithiophene, naphthodithiophene and the like are exemplified. A substituent is introduced by a covalent bond to the main chain skeleton for the purpose of controlling solubility and polarity of the π-electron conjugated block copolymer.

The polymer block (A) has, as a substituent, RnA that is an alkoxy group or an alkyl group having 1-18 carbon atoms, and involves a monomer unit having, in a portion of the chemical structure, at least one heteroaryl skeleton selected from the group consisting of a thiophene, a fluorene, a carbazole, a dibenzosilole and a dibenzogermole. In a case where the monomer unit has substituents in a plurality of portions, each substituent itself may be different from each other, but the monomer units included in the polymer block (A) each has preferably the same structure even in terms of structure of its substituent. However, other monomer units having different structure may be used, as long as the other monomer does not impair the effects of the present invention.

As a single type of alkoxy group of RnA having 1-18 carbon atoms, for example, methoxy group, ethoxy group, n-propyloxy group, isopropyloxy group, n-butoxy group, n-hexyloxy group, ethylhexyloxy group, cyclohexyloxy group, n-octyloxy group, n-decyloxy group, n-dodecyloxy group, and the like, are exemplified. The alkyl group or alkoxy group which constitutes RnA may be either linear, branched or cycloaliphatic, and two adjacent RnA may also form a ring by bonding with each other.

The polymer block (B) involves a plural types or kinds of monomer units having, in a portion of a chemical structure thereof, at least one heteroaryl skeleton selected from the group consisting of a thiophene, a fluorene, a carbazole, a dibenzosilole and a dibenzogermole; and having different substituents RnB different from each other and selected from an alkoxy group or an alkyl group having 1-18 carbon atoms which may be substituted with an alkoxy group, a halogen atom, a hydroxyl group, an amino group, a thiol group, a silyl group, an ester group, an aryl group, a heteroaryl group. In other words, it is required that the polymer block (B) should be a copolymer block comprising a plural types of monomer units which have the same main chain skeleton but have different substituents, or should be a copolymer block comprising a plural types of monomer units which have different main chain skeletons. If the polymer block (B) comprises a plural types of monomer units having different substituents, it is preferable that at least one substituent is a non-substituted alkyl group or alkoxy group.

As an alkoxy group of RnB, for example, an alkoxy group such as methoxy group, ethoxy group, n-propyloxy group, isopropyloxy group, n-butoxy group, n-hexyloxy group, ethylhexyloxy group, cyclohexyloxy group, n-octyloxy group, n-decyloxy group, n-dodecyloxy group, etc. can be exemplified. As an alkyl group or an alkoxy group which constitutes RnB may be either linear, branched or cycloaliphatic, and two adjacent RnB may also form a ring by bonding with each other.

As a halogen atom that may substitute RnB of the polymer block (B), for example, a fluorine atom, a chlorine atom, a bromine atom and an iodine atom are exemplified. As an alkyl group that is substituted with a halogen atom, for example, an ω-bromoalkyl group, a perfluoroalkyl group, and the like are exemplified.

As an amino group, for example, a primary or secondary amino group such as dimethylamino group, diphenylamino group, methylphenylamino group, methylamino group and ethyl amino group are exemplified.

As a thiol group, for example, a mercapto group, an alkylthio group can be exemplified. As a silyl groups, e.g. trimethylsilyl group, triethylsilyl group, tripropylsilyl group, triisopropylsilyl group, dimethylisopropylsilyl group, dimethyl-tert-butylsilyl group are exemplified.

As an aryl group, for example, phenyl group, 1-naphthyl group, 2-naphthyl group, 1-anthracenyl group, 2-anthracenyl group, 9-anthracenyl group, etc. are exemplified. These aryl groups may have a substituent such as an alkyl group, an alkoxy group, etc.

As a heteroaryl skeleton of a monomer unit that constitutes the polymer block (A) and the polymer block (B), a group having at least one thiophen ring in a portion of the chemical structure is exemplified. The thiophene ring may exist in the heteroaryl skeleton as one or more thiophene-2,5-diyl group, or may exist in the form of a condensed ring such as a thienothiophene, a dithienopyrrole, a benzodithiophene. More preferably, a group having a condensed thiophene ring or thiophene-2,5-diyl group having a substituent at least at 3-position, yet more preferably, a group having a condensed thiophene ring, is exemplified.

As a preferable monomer unit that constitutes the polymer block (A) or the polymer block (B), those including a group represented by the chemical formulas (1)-(19) are exemplified. The polymer block (A) or the polymer block (B) preferably comprises -a-b- monomer unit. -a- is preferably a monomer unit having any one of groups (a group comprising a donor type unit) represented by the chemical formulas (1)-(8), and -b- is preferably a monomer unit having any one of groups (a group comprising a unit having a ring serving as an acceptor) represented by the chemical formulas (9)-(19). Here, in the chemical formula (4), V3 is a monocyclic or polycyclic aryl group or heteroaryl group (q is an integer of 0-3) represented by —(Ar)q-, and is a portion of the main chain skeleton in the monomer unit. As V3, a thiophene ring is particularly preferable.

Further, as a specific example of the monomer units that constitute -a-b-, monomer units represented by the chemical formulas (20)-(31) are exemplified. For example, a monomer unit represented by the chemical formula -(2)-(9)- is a formula represented by the chemical formula (20), similarly, a monomer unit represented by the chemical formula -(2)-(17)- is a formula represented by the chemical formula (21), a monomer unit represented by the chemical formula -(2)-(18)- is a formula represented by the chemical formula (22), a monomer unit represented by the chemical formula -(2)-(19)- is a formula represented by the chemical formula (23), a monomer unit represented by the chemical formula -(3)-(9)- is a formula represented by the chemical formula (24), a monomer unit represented by the chemical formula -(4)-(9)- is a formula represented by the chemical formula (25), a monomer unit represented by the chemical formula -(4)-(13)- is a formula represented by the chemical formula (26), a monomer unit represented by the chemical formula -(4)-(17)- is a formula represented by the chemical formula (27), a monomer unit represented by the chemical formula -(4)-(18)- is a formula represented by the chemical formula (28), a monomer unit represented by the chemical formula -(4)-(19)- is a formula represented by the chemical formula (29), a monomer unit represented by the chemical formula -(5)-(9)- is a formula represented by the chemical formula (30), and a monomer unit represented by the chemical formula -(1)-(18)- is a formula represented by the chemical formula (31). Note that in the monomer unit of the present invention, as long as a polymer has a plurality of certain repeating structures in the polymer, a plurality of bonded heteroaryl structures (or, for example, a monomer unit of -a-b-) comprising a thiophene, a fluorene, a carbazole, a dibenzosilole or a dibenzogermole is also included as the monomer unit of the present invention. In other words, as long as the substituent groups are the same, a complete alternating copolymer block of the monomer unit -a- and the other monomer unit -b- is considered to be a homopolymer block of the monomer unit -a-b-.

As the substituent of the monomer unit of -a-b-, those represented by R1-R6 in the chemical formulas (1)-(31) can be exemplified. R1 is each independently an alkyl group having 1-18 carbon atoms which may be substituted. R2 is each independently a hydrogen atom or an alkyl group having 1-18 carbon atoms which may be substituted. R3 is each independently an alkoxy group or an alkyl group having 1-18 carbon atoms which may be substituted. R4 is each independently a hydrogen atom, a halogen atom, or an aryl group or an alkyl group having 1-18 carbon atoms which may be substituted. R5 is an aryl group, an alkylcarbonyl group, an alkyloxy carbonyl group, or an alkyl group having 1-18 carbon atoms which may be substituted, and R6 is a hydrogen atom or a halogen atom.

However, if the polymer block (A) comprises the monomer unit of -a-b-, at least one of the substituents of R1-R5 of -a-b- is RnA that is an alkoxy group or an alkyl group having 1-18 carbon atoms. If the polymer block (B) comprises the monomer units of -a-b-, at least one of R1-R5 of -a-b- is RnB which is an alkoxy group or an alkyl group having 1-18 carbon atoms which may be substituted with an alkoxy group, a halogen atom, a hydroxyl group, an amino group, a thiol group, a silyl group, an ester group, an aryl group or heteroaryl group. If the polymer block (B) comprises two or more types of monomer units of -a-b-, it is preferable that each monomer unit has a different RnB from each other.

The specific preferable example of -a- represented by the chemical formulas (1)-(8), is not particularly limited, but for example, a group represented by the following chemical formulas (32)-(38) can be exemplified.

In the chemical formulas (32)-(38), V2, R1, R2, R3 and R4 are the same as defined above.

A preferred embodiment of -b- represented by the chemical formulas (9)-(19), is not particularly limited, but for example, a group represented by the following chemical formulas (39)-(44) can be exemplified.

How KEYWORD MONITOR works... a FREEservice from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Pi-electron conjugated block copolymer and photoelectric conversion element or other areas of interest.###

Data source: patent applications published in the public domain by the United States Patent and Trademark Office (USPTO). Information published here is for research/educational purposes only. FreshPatents is not affiliated with the USPTO, assignee companies, inventors, law firms or other assignees. Patent applications, documents and images may contain trademarks of the respective companies/authors. FreshPatents is not responsible for the accuracy, validity or otherwise contents of these public document patent application filings. When possible a complete PDF is provided, however, in some cases the presented document/images is an abstract or sampling of the full patent application for display purposes. FreshPatents.com Terms/Support -g2-0.3553